Hi, I'm about to buy a Macbook and a digital piano to compose and record with Logic. I have been recommended to buy the Duet but have no idea what advantages this will give me. Will it improve the sound? Will it serve as a sound card? All I see is that it is a converter and interface for mic or guitars, etc... No MIDI, just USB directly from the piano.. So, where would the Duet come in? For the earphones? I'm new to recording and Mac's, so any explanations would be really helpful. Thanks!